Platform guidance system for shock test machine



Nov. 25, 1958 H. coHAN 2,861,449

PLATFORM GUIDANCE SYSTEM FOR SHOCK TEST MACHINE Filed March 23, 1955 2 Sheets-Sheet l Ll INVENTOR.

HENRY COHAN BY 74c. M

ATTORNEYS H. COHAN Nov. 25, 1958 PLATFORM GUIDANCE SYSTEM FOR SHOCK TEST MACHINE 2 Sheets-Sheet 2 Filed March 23, 1955 INVENTOR. HENRY COHAN ATTORNEYS TLATFORM GUIDANCE SYSTEM FOR SHOCK TEST MACHINE Henry Cohan, Riverside, Calif., assignor to the United States of America as represented by the Secretary of the Navy Application March 23, 1955, Serial No. 496,358

10 Claims. or. 73-12 (Granted under Title 35, U. S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to a cable and pulley system and more particularly to a cable guidance system including a plurality of cables anchored to a framework and trained over a series of pulleys mounted on a platform to allow the platform to fall freely while being constrained to a predetermined path and maintained at a predetermined attitude or inclination to the horizontal.

Structures have been previously designed to permit a platform to fall freely while in a horizontal position but these structures have required the use of rigid vertical guides and ways with sliding .or rolling members mounted on the platform and engaging the vertical ways.

These structures were expensive to construct, since they required a heavy, rigid and accurately machined assembly and the friction inherent in the sliders or rollers moving against the ways did not permit a completely free fall which is desirable particularly in such types of devices as shock testing machines. These prior devices could not be readily altered to change the inclination of the platform during fall and were extremely difficult to construct with sufiicient'accuracy and lack of friction to provide reproducible results in shock tests.

The present invention consists essentially of a rectangular framework having four cables anchored approximately at the four diagonally opposite corners of the top and bottom of the framework. Each of the cables is secured to a turnbuckle at one of the upper corners of the framework and is trained around a pulley on a horizontal axis at the corner immediately below, around a second pulley on a vertical axis at one adjacent corner of the platform, over a third pulley moun"- ed on a horizontal axis at the diagonally opposite corner and down to an anchor at the bottom of the structure at the diagonally opposite corner of the framework. By changing the length of any one or more of the cables by means of the turnbuckles or other similar adjusting means, the attitude or inclination of the platform can be varied so that any side or corner can be made to contact before the others.

One object of the present invention is to provide an improved guidance system for permitting thefree fall of a platform for use in certain devices such as shock testing machines.

Another object of the present invention is to provide a cheaper and simpler guidance system to allow a platform to fall freely while held in a horizontal or other predetermined attitude.

A still further object of the present invention is ,to provide a cable guidance system which will permit the free fall of a platform and may be readily adjusted. to vary the inclination of the platform during fall.

Still another object of the present invention is to provide a guidance system for a free falling platform 2 which minimizes friction while controlling the path and attitude of the platform during fall. A

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

Fig. l is a pictorial view of one preferred embodiment of the present invention, and

Fig. 2 is a pictorial view illustrating another embodiment constructed in accordance with the present invention.

Referring now to the drawings in detail, the preferred embodiment of the present invention illustrated in Fig. 1 consists of a rectangular framework 11 which may be built from suitable timbers having sufficient strength or from other structural members formed of steel, aluminum or other materials. This framework may be suitably braced where desired and provided with suitable means (not shown) for raising the platform after the fall and a bed of sand or a holder for lead blocks (not shown) to act as a bed for receiving the platform at the end of the fall and providing the desired type and shape of shock Waves.

A platform 12 is likewise constructed of wood or other suitable material and may be provided with means for attaching a test specirnan on its upper surface and ribs or other forms of projection (not shown) for penetrating the sand bed or lead blocks.

The platform 12 is provided with three pulleys on each corner thereof which may be mounted in several different manners one of which is illustrated wherein one pulley 13 is mounted on a substantially horizontal axis on the long side of the platform near the upper corner, a second pulley 14 is mounted on a vertical axis in a recess 15 formed in the corner of the platform, and a third pulley 16 is mounted on a substantially horizontal axis near the lower corner of the short side of the platform.

Pulleys 17, 18, and 19 are similarly mounted in an adjacent corner and pulleys 20, 21, and 22 are similarly mounted in the other adjacent corner. Mounted'in the far corner of the platform are the pulleys 23, 24, and 25.

The cables 26, 27, 28 and 29 are fastened to the upper portion of the framework by means of turnbuckles 31, 32, 33 and 34, with the opposite ends secured to the bottom of the framework by means of eyes 35, 36, 37 and 38.

The cable 26, as shown in Fig. 1, is trained over the pulleys 13, 21 and 25 and secured to the eye 35. The cable 27 is attached to the turnbuckle 32 and is trained over the pulleys 17, 24, and 22 and is attached to the eye 36. Cable 29 passes over pulleys 23, 18 and 16 and is attached to the eye 38. Cable 28 passes over pulleys 20, 14 and 19 and is secured to eye 37.

By adjustment of the turnbuckles 31, 32, 33, and 34 it will be apparent that the platform 12 may be set in a ,1 horizontal plane and Will maintain this attitude during its'fall to the bottom of the framework. If turnbuckles 32, and 34 are taken up to shortenthe effective length of the cables 27 and 29 the side of the platform mou'nting pulleys 17 and 23 will be raised relative to the opposite edge. Obviously, by adjustment, of the turnbuckles any desired inclination may be obtained.

A modification of the cable guidance system of the present invention is illustrated in Fig. 2 wherein the platform 42 is provided with a pair of pulleys 43 and 44 mounted on a substantially horizontal axis in the recess 45 formed in one corner of the platform 42. A pair of pulleys 46 and 47 are similarly mounted in one of the adjacent corners and pulleys 48 and 49 are mounted similarly in the other adjacent corner ofthe platform 42. In the far corner a pair of pulleys 51 and 52 are mounted in a similar manner.

The cables-53, 54, "55 and 56 may be mounted and attached to a framework in the same mannerasthe cables 26, 27, 28 and 29illustratedinf Fig. 1. Each of the cables is trained aroundone of the upper pulleys and extends through the interior of the platform 42 and over the diagonally opposite pulley down to the lower fastening means. For example, cable 54 extends over pulley 46 through the platform 42, over pulley 49 and down. Similarly cable 53 extends over pulleys 43 and 52, cable 55 extends over pulleys 48 and 47, and cable 56 extends over pulleys 51 and- 44.

It will be apparent that. both modifications, of the present invention will function in substantiallythe same manner. The platforms 1-2 and 42 will each fall in a substantially vertical path within the supporting framework and will maintain the attitude or inclination as determined by the relative lengths of the four cables, thus providing a cable guidance system in three dimensions.

While the framework 11 and the platforms 1-2 and 42 have been illustrated and described as having a rectangular shape which will be adaptable for most uses, in some cases it may be desirable to use a triangular or other shape of platform with 3 or more cables and with a suitable arrangement of pulleys and anchors. Other con ventional means may be used for varying the effective length of the cables, or cables of different lengths may be used for special applications.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

l. A platform guidance system comprising a plurality of cables and a platform adapted to be guided 'by said cables within a framework, said platform having a plu- V rality of pulleys mounted thereon, each of said cables being adapted to be attached at its opposite ends tothe top and bottom of the framework on diametrically opposite sides thereof, said cables being trained over one pulley on one side of said platform and another pulley on a diametrically opposite side of said platform.

2. A platform guidance system comprising a platform adapted to be mounted within a framework encompassing said platform during a free fall, a plurality of pulleys, certain of said pulleys being mounted for rotation on said platform on a substantially horizontal axis, and a plurality of cables each adapted to have one end secured to the upper portion of said framework and the opposite end secured to the lower portion of said framework, each of said cables being trained over one of the pulleys mounted adjacent one side of said platform and over another pulley mounted adjacent another diagonally opposite side of said platform.

3. A platform guidance system comprising a supporting framework, a plurality of cables and a platform adapted to be supported by said cables within said framework said platform having at least two pulleys mounted at each of several positions adjacent the periphery thereof, each of said cables being attached at its opposite ends to the top and bottom of said framework on diametrically opposite sides thereof, said cables being trained over one pulley at one position on said platform and another pulley at a diametrically opposed position on said platform.

4. A platform guidance system comprising a platform, a supporting framework adapted to encompass said platform during a free fall, a plurality of pulleys mounted for rotation adjacent each of four-spaced positions on said platform, at least two of said pulleys being mounted 4 on asubstantially horizontalaxis, four cables each having one end secured to the upper portion of said framework and the opposite end secured to the lower portion of said framework at a diametrically opposed position, said cables being trained over. one of the pulleys mounted at one position on said platform and over another pulley mounted at a diametrically opposed position on said platform, and means of saidcables.

5. A platform guidance system comprising a supporting framework, a plurality of cables, a platform adapted to be guidedby said, cables within said framework, said platform having at least two pulleys mounted adjacent each of the corners thereof, each of said cables being attached at its opposite ends to the top and bottom of said framework on diametrically opposite portions thereof, said cables being trained over one pulley at one corner of said platform and another pulley at a diametrically opposed corner of said platform, and means for adjusting the effective length of each of said cables.

6. A platform guidance .system comprising a platform having at least three corners, a framework adapted to encompass said platform during a free fall, a plurality of pulleys mounted for rotation adjacent each of the corners of said platform, at least two of said pulleys being mounted on a substantially horizontal axis, a plurality of cables each having one end secured to the upper portion of said framework and the opposite end secured to the lower portion of said framework at a diagonally opposed position, each of said cables being trained over one of the pulleys mounted at one corner of saidplatform and over another pulley mounted at a diagonally opposed corner of said platform, and means for adjusting the effective length of each of said cables.

7. A platform guidance system comprising a platform having at least three corners, a supporting framework adapted to encompass said platform during a free fall, said platform having two pulleys mounted on a substantially horizontal axis adjacent each of the corners thereof, said platform having a third pulley mounted on a vertical axis between said two pulleys adjacent each of the corners thereof, and a plurality of cables each secured at one end to the upper portion of said framework and at the opposite end to the lower portion of said framework, each of said cables extending from the upper portion of said framework over the uppermost pulley at one corner of said platform and around the intermediate pulley at an adjacent corner thereof and over the lowermost pulley on another corner of said platform and down to the lower portion of said framework.

8. A platform guidance system comprising a platform having at least three corners, a supporting framework adapted to encompass said platform during a free fall, said platform having two pulleys mounted on a substantially horizontal axis adjacent each of the corners thereof, said platform having a third pulley mounted on a vertical axis between said two pulleys adjacent each of the corners thereof, a plurality of cables each secured at one end to the upper portion of said framework and at the opposite end to the lower portion of said framework, each of said cables extending from the upper portion of said framework over the uppermost pulley at one corner of said platform and around the intermediate pulley at an adjacent corner thereof and over the lowermost pulley on another corner of said platform and down to the lower portion of said framework, and means for adjusting the effective length of each of said cables.

9. A platform guidance system comprising a platform, a supporting framework adapted to encompass said platform during a free fall, said platform having two pulleys mounted on a substantially horizontal axis at each of several positions adjacent the periphery thereof, a plurality of cables each'secured at one end to the upper portion of said framework and at the opposite end to for adjusting the length of each the lower portion of said framework, each of said cables extending from the upper portion of said framework over the uppermost pulley at one position across said platform and over the lowermost pulley at a diametrically opposed position to the lower portion of said framework.

10. A platform guidance system comprising a platform having at least three corners, a supporting framework adapted to encompass said platform during a free fall, said platform having two pulleys mounted on a substantially horizontal axis adjacent each of the corners thereof, a plurality of cables each secured at one end to the upper portion of said framework and at the opposite end to the lower portion of said framework, each of said cables extending from the upper portion of said framework over one of the pulleys at one corner of said platform across said platform and over one of the pulleys at a diagonally opposed corner of said platform and down to the lower portion of said framework, and means for adjusting the length of said cables.

References Cited in the file of this patent UNITED STATES PATENTS 1,710,442 Warshaw Apr. 23, 1929 2,645,931" Johnson July 21, 1953 2,656,711 Tschudi Oct. 27, 1953 FOREIGN PATENTS 833,872 France Aug; 1, 1938 1,049,888 France Aug. 26, 1953 

